Possible Existence of a Transition Point between β- and γ-Sulphur

Abstract

γ-SULPHUR, the metastable monoclinic modification first described crystallographically by Muthmann¹, is frequently obtained when a thin film of molten sulphur between a slide and cover slip is caused to solidify by chilling. Using such preparations, we have recently made some preliminary determinations of the linear rates of transformation of this form into both α- (rhombic) sulphur and β-sulphur, the monoclinic modification stable above 96°, as an extension of previous studies of the linear rate of transformation of β- into α-sulphur^2–4. The smoothed results are shown in Fig. 1, which also gives those for the β- to α-transformation. The three curves intersect at A, B and C, and although the temperature co-ordinates given for these points, namely, 12°, 55° and 75° respectively, can only be regarded as approximate at present, their existence is not in any doubt, since they have been confirmed by a number of observations of the relative rates of the transformations on slides on which all three forms were present.